1. Field of the Invention
The present invention relates to a cancer therapeutic instrument for use in treatment for cancers and neoplasm, and more particularly a cancer therapeutic instrument for use in treatment for the cancers originated, for example, in an area which involves a great deal of difficulty in performing a resection operation, the organs and the like, for instance, pancreatic carcinoma, lung cancer, brain tumor, cancers originated in the brain stem area, and for the cancers which are unfavorable to be resected from the point of view of beauty and maintenance of function, for example, breast cancer, head and neck cancer, tongue cancer and uterine cancer.
2. Description of the Related Art
Currently, cancer is one of the most terrible diseases which is left to mankind, and elucidation of its fundamental cause and therapy; and are in a developing state.
As typical therapy, which is considered at present to be effective, surgical resection, radiation therapy and chemotherapy are well known and most frequently employed.
Among those therapeutic methods, the surgical resection method is deemed to be most effective and is most frequently employed. On the other hand, for malignant tumors originated in the deep area of the body for which the surgical resection method cannot be employed, radiation therapy and chemotherapy are frequently used in combination. However, it often happens that both radiation therapy and chemotherapy involve strong adverse reaction, and the radiation therapy and chemotherapy are remarkably lower in complete cure rate in comparison with the surgical resection method and involve danger of relapses.
Recently, in view of the foregoing, there is hastened vigorously a study of cancer therapy according to physical therapy which involves no adverse reaction. As typical therapy, there are hyperthermia and phototherapy using a photosensitizer.
The hyperthermia is involved in a way such that a cancer cell is extinguished through heating and/or cooling thereof. It has been reported that keeping a cancer cell at a temperature, for example, higher by +5.degree. C. than body temperature, which would cause merely relatively less damage to peripheral normal cells, throughout a definite time, alone may bring a great treatment effect.
On the other hand, the phototherapy is based on such a mechanism that irradiation with a specified wavelength of activation light on a cell absorbing a photosensitizer leads to an absorption of optical energy by the photosensitizer, so that activating oxygen, which will destroy the cell, emanates. This treatment utilizes the fact that an excretion ratio of the photosensitizer after injection thereof is extremely lower in a cancer cell in comparison with a normal cell, specifically, less than 1/3 (about 1/5).
The present invention is involved in the phototherapy, and thus the phototherapy will be described in detail hereinafter.
FIG. 9 is a graph showing a relation between time elapsed wherein a time point when an ATX-S10, which is one of photosensitizers, is injected into the body, is selected as a starting point and the relative concentrations of the ATX-S10 remaining in cells. The graph PN denotes the residual concentrations of the ATX-S10 within the normal cells; and the graph PC the residual concentrations of the ATX-S10 within the cancer cells.
When a certain standby time lapses (about 3 hours) after plenty of photosensitizer is injected into the affected part and its peripheral cells through a direct injection of the photosensitizer into the affected part, an intravenous injection and the like, the normal cells have discharged almost all the photosensitizer, whereas there appears such a state (light treatment feasible state) that almost all the photosensitizer stays in the cancer cells. In such a light treatment feasible state, irradiation with a specified wavelength of activation light leads to an emanation of activating oxygen, which will destroy the cells, within the cancer cells in which almost all the photosensitizer stays, while almost no activating oxygen emanates within the normal cells which have discharged almost all the photosensitizer, whereby the cancer cells are selectively extinguished.
Duration (the term of validity for light treatment) of the light treatment feasible state after an injection of the photosensitizer starts after 3 hours since injection of the photosensitizer and terminates after 14 hours with which the cancer cells have discharged almost all the photosensitizer. Incidentally, FIG. 9 shows an ATX-S10 by way of example. The standby time after injection of the photosensitizer and the term of validity for light treatment will vary about one order of magnitude in accordance with the type of photosensitizer.
The gist of this treatment resides in the point that activation light is continuously projected onto the affected part as uniformly as possible during the term of validity for light treatment, and the amount of irradiation light is controlled in such a manner that cell-inside-concentrations of activating oxygen which causes cells to be extinguished is restricted to a very low value such that the death rate of the normal cells is in the permitted limit within the normal cells, whereas the cell-inside-concentrations of activating oxygen assumes a value such that the death rate of the cancer cells is nearly 100% within the cancer cells.
To project the activation light onto the affected part, hitherto, an optical fiber is directly inserted into the affected part and activation light is transmitted through the optical fiber. However, according to this scheme:
(a) Since the optical fiber cannot be moved during the treatment, irradiation area or the therapeutic area is extremely limited;
(b) To project light from the tip of the optical fiber in all directions, it is necessary to cut the tip of the optical fiber, for example, in a cone shape. Processing for such an optical fiber is difficult and then the optical fiber is very expensive;
(c) To perform the treatment repeatedly, it is necessary to repeat insertion of the optical fiber whenever the treatment is performed. It is a great burden to both a patient and a doctor;
(d) Since the therapeutic area is narrow, it is difficult to cure completely large cancers and tumors; and
(e) There are needs of sterilization of the optical fiber before use and re-sterilization of the optical fiber after each use or solid waste disposal. Usually, it is needed to provide an optical fiber having a length not less than 1 m, and the optical fiber is of a compound material. Consequently, the sterilization and the solid waste disposal are troublesome and thus the optical fiber is poor in operational efficiency.